Numerical study of three-dimensional Kolmogorov flow at high Reynolds numbers

摘要: High-resolution numerical simulations (with up to 2563 modes) are performed for three-dimensional flow driven by the large-scale constant force fy = F cos(x) in a periodic box of size L 2π (Kolmogorov flow). High Reynolds number is attained solving Navier-Stokes equations with hyperviscosity (-1)h+1Δh (h 8). It shown that mean velocity profile Kolmogorov nearly independent and has ‘laminar’ form vy V eddy viscosity. Nevertheless, highly turbulent intermittent even at large scales. The intensities, energy dissipation rate various terms balance equation have simple coordinate dependence + b cos(2x) a, constants). This makes good model explore applicability turbulence transport approximations open time-dependent flows. turns out standard expression effective (eddy) viscosity used K-[Escr ] models overpredicts regions high shear should be modified account non-equilibrium character flow. Also scales anisotropic but isotropic small important problem local isotropy systematically studied measuring longitudinal transverse components spectra crosscorrelation velocities velocity-pressure-gradient spectra. Cross-spectra which vanish case decay only algebraically somewhat faster than corresponding correlations. verified pressure plays crucial role making locally isotropic. demonstrated may considered approximately ten times smaller scale